In order to meet the constantly increasing demand by mobile terminals for higher data rates with limited wireless spectrum resource, cognitive radio and spectrum aggregation technologies have attracted much attention due to its capacity in improving spectrum efficiency. Combing cognitive relay and spectrum aggregation technologies, in this paper, we propose a dynamic spectrum aggregation strate...

In spectrum-sharing systems where the secondary user (SU) opportunistically accesses the primary user (PU)’s licensed channel, the SU should satisfy both the transmit power constraint of the SU transmitter and the received power constraint at the PU receiver. This letter studies the ergodic capacity of spectrum-sharing systems in fading channels. The ergodic capacity expression along with the o...

This paper investigates from the physical layer security (PLS) perspective the fundamental issues of mode selection and spectrum partition in cellular networks with inband device-to-device (D2D) communication. We consider a mode selection scheme allowing each D2D pair to probabilistically switch between the underlay and overlay modes, and also a spectrum partition scheme where the system spectr...

As the increased demands of wireless channel, there is the need for the proper utilization of the spectrum which leads us to the new technique called cognitive radio technologies. Static spectrum allocation need to merge with a technique where it can be share for the proper utilization of the spectrum. Higher capacity requirement is of great need. As long as the technology is been evolving the ...

In this paper, we have used density functional perturbation theory (DFPT) and Pseudo-potential method to calculate the phonon spectrum, phonon density of states (DOS), specific heat capacity and mechanical properties of (5,5) armchair and (9,0) zigzag Single Wall Carbon Nanotubes (SWCNTs). Our calculations show that Young’s modulusfor (5,5) and (9,0) nanotubesare higher than 1TPa. We have also ...

Femtocells and WiFi are often presented as opposing technologies. The reality is that both have a vital role to play in supporting future mobile traffic growth. In many cases both technologies will eventually be employed in a single box with access via an intelligent mobile deviee that will automatically select the best option. Deploying Femtocells in WiFi hotspots would let access providers ad...